1. Field of the Invention
The present invention relates to a tape running device for running an endless magnetic tape and, more particularly, to a tape running device useful particularly for mass-producing the duplicate magnetic tapes of a mother magnetic tape.
2. Description of the Prior Art
A tape running device capable of running an endless mother magnetic tape is necessary for mass-producing the duplicate magnetic tapes of the mother magnetic tape by recording data recorded in the mother magnetic tape in virgin magnetic tapes.
Japanese Patent Laid-open (Kokai) No. 62-57154 discloses a magnetic tape running device for running an endless magnetic tape.
Japanese Patent Laid-open (Kokai) No. 62-139108 discloses another magnetic running device for running an endless magnetic tape, provided with a plurality of guide rollers.
These known magnetic tape running devices each has a tape storage chamber provided with a tape outlet opening and a tape inlet opening, for storing the most portion of a long, endless magnetic tape in a zigzag arrangement. The endless magnetic tape is pulled out from the tape storage chamber through the tape outlet opening and is returned through the tape inlet opening into the tape storage chamber to run the endless magnetic tape repeatedly.
The former known type running device has the following drawbacks.
First, it is possible that the magnetic tape is turned over in drawing out the magnetic tape from the tape storage chamber, because the magnetic tape is stored in the tape storage chamber in random layers, but the magnetic tape is rarely turned over in a practical tape running operation when the magnetic tape has a sufficiently large width on the order of 12.8 mm and a thickness greater than 50 .mu.m, and the tape storage chamber is designed properly, because such a magnetic tape is strong enough to resist a force tending to turn the magnetic tape over. However, a magnetic tape having a small width on the order of 8 mm or 3.8 mm and a thickness on the order of 18 .mu.m is turned over frequently, because such a narrow and thin magnetic tape is scarcely resistant to a force tending to turn over the magnetic tape.
Secondly, since the magnetic tape is folded zigzag in the tape storage chamber, the magnetic tape is liable to be creased when the magnetic tape is pulled suddenly at a high pulling speed. Although insignificant in low-density recording, creases in the magnetic tape are significant problem in high-density recording, and the magnetic tape must not be creased in high-density recording.
The latter know tape running device provided with a plurality of guide rollers for guiding an endless magnetic tape for storage in the tape storage chamber is designed to deal with a magnetic tape having a sufficiently high tensile strength. A narrow and thin magnetic tape, such as a magnetic tape having a width on the order of 3.8 mm or 8 mm and a thickness on the order of 18 .mu.m, will be exposed to an excessive tensile force. Furthermore, the length of the endless magnetic tape which can be stored in this tape running device is fixed, and the tape running device is unable to deal with variation in the length of the magnetic tape.